Tailoring the Mo:V Ratio in MoO3/V2O5 nanocomposites for high-efficiency surface adsorption of methylene blue

In this study, synthesis of MoO₃/V₂O₅ nanocomposites (NCs) has been reported using a simple, time-efficient, and cost-effective wet chemical approach. Various MoO₃/V₂O₅ NCs (MV-30, MV-50, MV-70) have been prepared by controlling the Mo:V ratio. The synthesized nanocomposites were characterized using XRD, Raman spectroscopy, FESEM, EDS, HRTEM, zeta potential, BET-BJH, TGA, and FTIR analyses. XRD patterns confirmed a gradual increase in MoO₃ peak intensity with rising Mo content. The MV-50 NCs exhibited an enhanced specific surface area of 16.2 m²/g and an average pore size of 3.6 nm. The synthesized NC has been utilised for Methylene Blue (MB) dye adsorption. The MV-50 NCs show the best dye adsorption in comparison to other NCs, which is attributed to higher specific surface area and larger pore size. At an initial dye concentration of 20 mg/L, neutral pH, and ambient temperature, 99.9 % of the dye was adsorbed within 8 minutes. Kinetic studies revealed that MB adsorption followed the pseudo-second-order model, suggesting chemisorption. The equilibrium data aligned well with the Langmuir model, indicating monolayer adsorption with a maximum capacity of 737.6 mg/g. Thermodynamic parameters confirmed the process was spontaneous and endothermic, supported by negative Gibbs free energy (8 kJ/mol), an enthalpy (∆H°) of 6.58 kJ/mol, and increased randomness (∆S° = 47.3 J/mol·K) at the solid–liquid interface. Post-adsorption analyses, including TGA, FTIR, BET, EDS, and FESEM, demonstrated the structural stability of MV-50. Its reusability and consistent performance in industrial wastewater samples containing interfering ions highlight its potential for practical environmental remediation.